The present invention relates generally to bracket assemblies for heavy loads. Angle brackets and bracket assemblies designed for heavy loads are well known in the art.
Angle brackets often comprise three main structural components, a horizontal, a diagonal and a vertical leg, which are interconnected so as to define, in load-bearing shape, a substantially triangular bracket. Bracket assemblies typically comprise an angle bracket of the type described above which is further attached to other members, such as an upper bracket arm and a lower bracket arm. An example of such a bracket assembly is disclosed in U.S. Pat. No. 2,342,427 to Riblet which is incorporated herein by reference. In U.S. Pat. No. 2,342,427, a lower bracket arm is shown attached to an angle bracket by a bolt which passes through a preformed hole in both the vertical leg and the diagonal leg.
In use, angle brackets and bracket assemblies are often mounted onto different surfaces to create various support structures.
For example, it is well known in the art to mount a pair of angle brackets directly onto a flat wall surface to create a shelf. A shelf is created by placing a horizontal plank across the pair of angle brackets. In this application, the vertical leg of each angle bracket is often provided with upper and lower keyslots or even the vertical leg may be replaced by the wall with out loss of strength. The keyslots can accommodate screws, nails or the like which extend through the angle bracket and into the wall surface to securely mount the angle bracket onto the wall surface.
It is also well known in the art to mount each of a pair of bracket assemblies onto an associated upright, such as a post or beam, to create a scaffold. A scaffold is created by securing the bracket arms of each bracket assembly onto its associated upright. A horizontal plank is then placed across the angle bracket of each bracket assembly to form the scaffold. In one application, each bracket assembly can be repositioned at varying heights along its associated upright to adjust the height of the scaffold.
In the art, angle brackets typically fall into two categories: one-piece angle brackets and multiple-piece angle brackets.
One-piece angle brackets include two or three legs which are formed from a single piece of material and which are interconnected so as to define a triangular bracket, the mounting surface being considered to be the third leg for one-piece angle brackets having two legs. For example, it is well known in the art for an angle bracket which can be used for shelving and other light loads to be formed entirely from a single sheet metal blank, one or more legs of the angle bracket being strengthened by longitudinal folding in the metal blank.
Multiple-piece angle brackets typically comprise two or three separate legs, as well as additional fastening components, which are interconnected so as to define a triangular bracket. U.S. Pat. No. 4,360,181 to Burkholder is a example of a multiple-piece angle bracket in which the vertical member of the angle bracket is a section of an extended upright. Multiple-piece angle brackets commonly comprise a plurality of structurally strong legs and a plurality of connecting means which may include nuts, bolts, rods and pins all interconnected to define, often with an additional vertical member, a triangular bracket. Due to the multitude of parts required, multiple piece angle brackets are more costly to manufacture and assemble than one-piece angle brackets.
Compared to one-piece angle brackets, however, it should be noted that the permissible strength of the parts included in multiple-piece angle brackets increase the overall strength of the angle bracket. In particular, it has been found that when compared with one-piece angle brackets, multiple piece angle brackets are considerably stronger at corners, each corner corresponding to the juncture of adjoining legs. As a consequence, multiple piece angle brackets are used for scaffolding and other heavy loads because they are capable of withstanding greater amounts of force than one-piece angle brackets.
In U.S. Pat. No. 5,257,766 to Riblet, which is incorporated herein by reference, there is disclosed an angle bracket constructed from a single piece metal blank. The bracket is of a substantially triangular shape. In one embodiment of the invention, the bracket has legs of U-shaped cross-section for strength. A method is disclosed for constructing the bracket from the metal blank which includes the steps of folding the metal blank along transverse fold lines to form its triangular shape. The method also includes the steps of folding the metal blank along longitudinal fold lines to form its U-shaped cross-section.
One-piece angle brackets, in which the bendable interconnections are strengthened by interlocking mechanical irregularities, tabs and slots for example, as described in U.S. Pat. No. 5,257,766 to Riblet, are extremely desirable since they combine the simplicity of the construction of one-piece angle brackets with the strength of the multiple-piece angle brackets. The simplicity of its construction results in substantial cost savings due to the need for less inventory control and greater ease in manufacture and assembly.
Angle brackets constitute the major component of bracket assemblies. Specifically, bracket assemblies comprise an angle bracket with additional parts attached to the corners of the angle bracket between the diagonal leg and the horizontal leg and the vertical leg, if present. In U.S. Pat. No. 2,854,293, a bracket assembly is disclosed in which a lower bracket arm is attached to the intersection between the diagonal and vertical legs of an angle bracket by a bolt. The bolt attaching the diagonal leg to the horizontal leg could also be used to attach an extension arm to the horizontal leg. Either or both of these arrangements are considered bracket assemblies.
Although the specifications and claims define an angle bracket as having a horizontal, a diagonal and a vertical leg, it should be stated that the features of the this invention are contained in the elements meeting at the intersection of the horizontal and diagonal legs. The vertical leg is included to simplify the figures and claims.